Process of protecting sand molds and cores



Patented May 19, 1931,

UNITED STATES rArENr orrlca EUG-ENE A, IBALSLEY, Q1 WHEELING,WES'IVVIRGINIA, LUOIEN I. YEOMANS, OI

CHICAGO, IILINOIS, ASSIGNOBS 'I'O'LUQIEN I. YEDHLNS, INC, 01' CHICAGO,ILLINOIS, 1

a conronarron or more P3001388 OF PROTECTING QMIOLDS Io Drawing. 7

' In the preparation ofsand molds in which molten metal is to bepoured,- it iscustomary to reinforce fragile sections in some instancesand to protect corners, small bosses, thin ribs and other projectingsurfaces where the wash of the metal is liable to break off or cut awaya portion of the moldsurface, by using ordinary nails of various sizeswhich are inserted in the sand body by the molder. in such a 10 mannerthat the nail heads are flush with the mold. surface and constitute apart thereof.

On certain classes of work the expense involved in thus protecting themold from wash is an item of consequence, and it is not uncommon forfoundries making irregular sections of large steel castings to use asmany as twenty pounds of nails, per ton output of the entire foundry,thereby adding a cost of a dollar a ton to the average cost of castings.

This is not the only expense, or even the prln cipal expense itemoccasioned by their use. The proper placing of the nails requires careand skill and involves a considerable labor cost. The expense of shakingout molds after casting is increased, particularly in the caseApplication jfled July 5,

of steel castings as the nail heads are melted p by the molten metal andwelded to the casting. -The labor entailed in chipping off the nails andcleaning the casting is a further item of expense. I

We have discovered that thesurfaoes of v asandmold'maybestructurallstrengthened and protected againstwash o molten metal j by. upon suchsurfaces a thin layer 0 metals .'.for this purpose,- buthave foundaluminum well adapted to the requirements, and

prefer to use metals which have. ama'rked affinity for oxygen or whichupon melting tend 4o to .-remove rather than increase the gaseous'contentof the metalsfrom which the. casting is tobemade'. To-.-applysuch-a coating we prefer' to the welllmown Schoopfsp'ray .When -'sprayed:uponlthem'old, the mtlaii 451jmetal penetrates intothe among I I H h II S p v molten'metal. We may use a variety of;

1929. Serial ll'o. 878,280.

the grains of sand and roduces a protective coating which adheres rmlytothe mold.

Cores, forming part of a mold, may be treated in this way to expeditecleaning processes after the casting is poured, and struc- P turalstrength and surface protection against washing may be secured upon dryor green has been left in the casting because of the difliculty' ofremoving it.

We do not coat the entire surface of the mold or core, but only thosesurfaces -(and particularly fragile projecting portions) which requirereinforcement against the wash of the metal. It would be impracticableand even dangerous to coat the entire surface, as the heat of the metalcauses vaporization of volatile substances in the mold or core, as, forexample, the binder compounds emblo wprocess the vapors ployed in coremaking. "If'the entire surface.

damage the 'casting'by the formation of.

escape from the uncoated surfaces of the mold i or core.

The method herein disclosed of protectin sand molds from'wa'sh ischeaper than that o I pause of nails, reduces the cost of cleaning thecastings, and in some results. in a smoother product. A

- This application is a continuation in gut of our application SerialNo. 275,956, ed *Ma 'maaa ,We. claim as ourinlviention: Theprocess'ofstructurally strengthening inserting nails in the molds, obviates theex- 5 the fra 'le projections and the surfaces adjacent t ereto of asand mold or core to protect such projections from wash which c0n--sists in spraying with molten metal such projections and adjacentsurfaces, the remaining surface area being not coated with metal inorder to permit escape of vapors from such uncoated surfaces.

In testimony whereof we have hereunto aflixed our signatures.

EUGENE A. BALSLEY. LUCIEN I. YEOMANS.

